1. Field of the Invention
This invention relates to a novel technique to increase oxygen partial pressure in the blood stream of mammals.
2. Description of the Prior Art
In applicants' prior applications, now U.S. Pat. Nos. 3,853,993 and 3,788,468, applicant disclosed that certain water-soluble carotenoids has been observed to possess quite unique properties. In particular, these water-soluble carotenoids have been found to increase the diffusivity of oxygen through aqueous media. Applicant theorized that this phenomenon might be applied to effect desirable biological effects. In particular, applicant theorized that if oxygen diffusivity in aqueous media could be enhanced, that this effect could be applied to increase the diffusivity of oxygen in blood. Applicant theorized further that by increasing the diffusivity of oxygen in the blood, atherosclerosis, which has long been theorized to be a disease resulting from local hypoxia of the vascular walls, could be successfully treated. This theory was applied to certain test animals, and, to the satisfaction of the inventors, the theory was proven to be correct, and in fact, a seemingly successful treatment of atherosclerosis was obtained.
It has been known that it would be desirable to increase the partial pressure of O.sub.2 in the bloodstream for the treatment of a variety of disorders. This treatment is known as oxygen therapy, and is currently carried out by placing the subject in an oxygen tent. This treatment is of particular importance in respiratory diseases such as asthma, pulmonary emphysema and cistic fibrosis, but is also frequently used in intensive care units for treating many other diseases such as myocardial infarctions, for example.
The uptake of oxygen by the blood in the lungs is assumed by most people to be perfusion-limited, rather than diffusion-limited. This means that it is the rate of blood flow through the capillaries in the lungs which determines how much oxygen is taken up by the blood (See: T. C. Ruch and D. D. Patton, "Physiology and Biophysics", W. B. Saunders Do., Philadelphia, 1965, p. 736; J. B. West, "Respiratory Physiology - the Essentials", Williams and Wilkins, Baltimore, 1974, p. 26; B. A. Schottelius and D. D. Schottelius, "Textbook of Physiology", 17th ed., C. V. Mosly Co., St. Louis, 1973, p. 331). Thus, since it is difficult to increase the blood flow through the capillaries to the lungs, it is common to put people requiring increased oxygenation of their blood in oxygen tents where the partial pressure of oxygen varies from 40 - 60% (rather than the 21% in normal air). The invention described of using carotenoid to increase the partial pressure of oxygen in the blood is an alternative to using the oxygen tent. Although the principle through which it works may be due to diffusion increases, this is in contrast to the currently-accepted theory of perfusion limitation mentioned above. So it is possible that the effect of carotenoid of increasing the partial pressure of oxygen in the blood is not due to increasing the diffusivity of oxygen.
Applicant has now continued to study the biological properties of this most unusual class of compounds, with the result that a new biological property has been discovered which is the subject matter of this application.